Question

I’m working on a large project that consists of several sections, each with a varying number of slides.

I’m trying to dynamically create a navigation bar where the number of buttons correspond with the loaded section’s slides. The issue I have is setting the on/off appearance of the button as each slide loads.

I create the navigation bar when the section is created and the appearance of each button should be updated as each slide is loaded. I am trying to target each button using viewWithTag. The appearance is fine when the first slide of the section loads, but when I hit the next button everything disappears. Curiously, when clicking back to the first slide, everything appears as it should.

When a section is loaded, a mutable array of dictionary objects is created containing the necessary slide information. I have a class method (- (void) newbutton:(NSString *) title withIndex:(int) index atPosition:(int) Xpos) that is called from the Main View that creates a custom “ON” and “OFF” button through a for-loop, passing title and index arguments from a plist file. After that, the slide at index 0 is loaded.

Main View

- (void) findStory:(NSString *) presentation
{

    [model loadStory:presentation];

    int storyCount = model.currentStory.count;
    if (storyCount > 1) {
        int distribution = 700 / (storyCount - 1); // 700 = width of Navigation Rule
        int Xpos = 89; // 89 = X position of Navigation Rule

        // Build Navidation trail
        for (int i = 0; i < model.currentStory.count; i++) {

            NSLog(@"findStory(): Item Title: %@", [model.currentStory[i] objectForKey:@"name"]);

            [nav newbutton:[model.currentStory[i] objectForKey:@"name"] withIndex:i atPosition:Xpos];
            navButton = nav.button;
            navDot = nav.buttonDot;
            [self.navHolder addSubview:navDot];
            [self.navHolder addSubview:navButton];
            Xpos += distribution;
        }
    }

    [self newPage:model.pageIndex];
}

- (void)newPage:(int) index
{
    NSLog(@"newPage(): Requested page Index is %i", model.pageIndex);
    // Code that finds and loads the slide  

    // At the end the navigation appearance is set
    [self setNavAppearance:index];
}

- (void) setNavAppearance:(int) index
{
    NSLog(@"setNavAppearance(): Setting navigation appearance...");
    int storyCount = model.currentStory.count;

    if (storyCount > 1) {
        for (int i = 0; i < storyCount; i++) {
            int pressedIndex = i + 20;
            int viewTag = i;
            UIButton *onButton = (UIButton *)[self.navHolder viewWithTag:viewTag];
            if (i != index) {
                onButton.hidden = YES;
            } else {
                onButton.hidden = NO;
            }

            UIButton *offButton = (UIButton *)[self.navHolder viewWithTag:pressedIndex];
            offButton.hidden = NO;

        }
    }

    NSLog(@"setNavAppearance(): navigation appearance set.");
}

nav Class Method

- (void) newbutton:(NSString *) title withIndex:(int) index atPosition:(int) Xpos
{
    buttonIndex = index;

    button = [[UIButton alloc] init];

    int labelXPosition = (Xpos - 75);
    int dotXposition = (Xpos - 10);

    // ON Button
    buttonLabel = [[UILabel alloc] initWithFrame:CGRectMake(labelXPosition, 637, 150, 55)];
    buttonLabel.textColor = [UIColor blackColor];
    buttonLabel.font = [UIFont fontWithName:@"HelveticaNeue-CondensedBold" size:12];
    buttonLabel.textAlignment = NSTextAlignmentCenter;
    buttonLabel.lineBreakMode = NSLineBreakByWordWrapping;
    buttonLabel.numberOfLines = 2;
    buttonLabel.text = title;
    buttonLabel.backgroundColor = [UIColor clearColor];
    buttonLabel.textColor = [UIColor colorWithRed:0.047f green:0.337f blue:0.494f alpha:1.0f];
    [self.button addSubview:buttonLabel];

    dot = [[UIImageView alloc] initWithFrame:CGRectMake(dotXposition, 702, 20, 20)];
    [dot setImage:[UIImage imageNamed:@"buttonPressed.png"]];
    [self.button addSubview:dot];

    button.tag = buttonIndex;

    // OFF Button
    buttonDot = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    buttonDot.frame = CGRectMake(dotXposition, 702, 20, 20);
    buttonDot.backgroundColor = [UIColor clearColor];
    UIImage *dotImage = [UIImage imageNamed:@"button.png"];
    [buttonDot setBackgroundImage:dotImage forState:UIControlStateNormal];
    UIImage *dotImagePress = [UIImage imageNamed:@"buttonPressed"];
    [buttonDot setBackgroundImage:dotImagePress forState:UIControlStateHighlighted];

    int dotIndex = buttonIndex + 20;
    buttonDot.tag = dotIndex;

}

I’m not sure what’s going on. The -(void) setNavAppearance method runs every time a new page loads and should theoretically set the desired appearance.

I’d appreciate any help anyone could offer.

Thanks

Answer 1

As already noted in my comment;

Careful when using tag’s set to 0. If no tag is explicitely defined, zero is used. Hence anything that has no tag defined, will match zero.